BACKGROUND AND AIMS: Nonalcoholic steatohepatitis (NASH) is a common liver disease that may progress to cirrhosis and hepatocellular carcinoma. There is currently no approved pharmacological treatment for NASH. Phyllanthus urinaria is a commonly used hepatoprotective herb that ameliorates NASH in animal studies. We aimed to test the hypothesis that Phyllanthus was superior to placebo in improving histological nonalcoholic fatty liver disease (NAFLD) activity score. METHODS: This was a placebo-controlled parallel-group double-blind randomized controlled trial. Patients with histology-proven NASH were randomized to receive Phyllanthus or placebo for 24 weeks. The primary endpoint was change in NAFLD activity score from baseline to week 24. Secondary endpoints included changes in individual histological parameters, liver biochemistry and metabolic profile. RESULTS: We enrolled 60 patients (40 received Phyllanthus and 20 received placebo). The change in NAFLD activity score was -0.8±1.4 in the Phyllanthus group and -0.3±1.3 in the placebo group (P=0.24). The change in steatosis, lobular inflammation, ballooning and fibrosis was also similar between the two groups. Within the Phyllanthus group, although there was reduction in hepatic steatosis (-0.2±0.7; P=0.039) and ballooning grades (-0.4±0.5; P<0.001), the change was small and of limited clinical significance. Furthermore, there was no significant difference in the changes in alanine aminotransferase, aspartate aminotransferase, fasting glucose and lipid profile between the two groups. CONCLUSIONS: Phyllanthus is not superior to placebo in improving NAFLD activity score in NASH patients.